Recently, compact electric devices have been required in which a cable employed therein should have high flexibility. Therefore, a conductive tape having a wavy, corrugated and/or embossed pattern (defined a "wavy pattern"0 hereinafter) has been utilized for a shielding layer of an electric cable or an outer conductor of a coaxial cable.
In a conventional apparatus for manufacturing an electric cable, a cable core is inserted into a forming die with a conductive tape, and the cable core is drawn from the die together with the conductive tape, so that the conductive tape is formed around the cable core. In such an apparatus, the conductive tape is advanced by a guide belt independently of the cable core to relief the conductive tape from tension, so that the conductive tape is prevented from losing a wavy pattern formed thereon.
According to the conventional apparatus, however, there is a disadvantage in that tension of the conductive tape in the longitudinal direction thereof is not avoided sufficiently, because a difference in an advancing speed between the cable core and the guide belt occurs due to by friction between the guide belt and the inner surface of the die. Then, the conductive tape is twisted and pressured in the radial direction, so that the wavy pattern of the conductive tape is crushed. Therefore, the manufactured cable did not have good electrical and mechanical characteristics.